PetVille's population breeds 6 million

Yes, in just a mere week, the players of Zynga's newest Facebook game PetVille got together and bred like rabbits. Launched on December 3, the game's cartoon-like, cute gameplay, catchy song and a reliance on helping neighbors groom and clean house started a pet-loving movement that's been previously seen with the company's other games.

Considering that PetVille's biggest gain in players (roughly 1 mm players to nearly 6mm players today, says AppData) occurred over the past two days, fans of Zynga's brand of social gaming are fully embracing the the company's version of pet adoption.